Unit 3 Flashcards
Describe sound
Sound is a vibration that propagates as an audible mechanical wave of pressure and displacement
______ is what makes different instruments sound distinct even if they are playing the same pitch at the same intensity
Timbre (tone color, tone quality)
What are examples of timbre?
Overtones
Harmonics
Sound envelope
What are the components of the external ear?
Auricle (pinna)
Auditory canal
What is the function of the external ear?
Functions to gather sound toward the tympanic membrane
What are the components of the middle ear?
From ear drum to the oval window
Includes ossicles (malleus, incus and stapes)
Tympanic cavity
Auditory tube
What is the function of the middle ear?
Transfers sound energy to the oval window
What are the components of the inner ear?
Bony labyrinth
Membranous labyrinth
Cochlea
Vestibular system
_____ is the hollow cavity of the temporal bone
Bony labyrinth
______ and ______ are components in the membranous labrynth
Cochlea
Vestibular system
Cochlea functions in ______
Vestibular system functions in ______
Cochlea- sound detection
Vestibular system- balance detection
What is impedance matching?
due to the lever actions of the ossicles, the sound vibrations are transmitted to the round window with greater force
_________ is necessary because inner ear fluids have more inertia than air
Impedance matching (The sound vibrations are transmitted to the round window with greater force)
What 2 muscles are involved in the attenuation reflex?
Tensor tympani and stapedius
______ and _____ dampen vibrations during chewing, speech and other loud noises
Tensor tympani and stapedius
What is the origin and insertion, innervation and function of tensor tympani?
O: auditory tube
I: malleus
Innervation: CN V3
Function: tenses the tympanic membrane
what is the origin, insertion, innervation and function of the stapedius?
O: pyramidal eminence of temporal bone
I: stapes
Innervation: CN VII
Controls amplitude of sound waves entering the inner ear
Describe the cochlea shape
3 adjacent fluid filled tubes coiled into a shell shape
What are the names of the 3 adjacent fluid filled tubes that make up the cochlea?
Scala vestibuli (vestibular duct) Scala media (cochlear duct) Scala tympani( tympanic duct)
________ is a component of the cochlea that is thin and easily moves with sound vibrations
Scala vestibuli (vestibular duct)
_______ is a component of the cochlea that contains the organ of Corti
Scala media (cochlear duct)
______ is a component of the cochlea that ends at the round window and functions to connect to the scala vestibuli at the helicotrema
Scala tympani (tympanic duct)
What component of the cochlea contains endolymph?
Scala media (cochlear duct)
What components of the cochleae contain perilymph?
Scala vestibuli (vestibular duct) Scala tympani(tympanic duct)
What are the 2 membranes that separate the 3 tubes of the cochlea?
Vestibular membrane (Reissner’s membrane) Basilar membrane
_______ is located between the scala vestibuli and the scala media
Vestibular membrane (Reissner’s membrane)
_______ is located between the scala media and the scala tympani
Basilar membrane
______ contains hair cells
Organ of Corti
Where does the organ or Corti lie?
On top of the basilar membrane
What are the Mechanoreceptors for sound called And where are they located?
Hair cells
Organ of Corti
What are the nerve fibers that are formed by stimulation of hair cells?
Cochlear nerve
What are the hair cell embedded in?
The tectorial membrane
Describe the distribution of sound as it hits the tympani membrane causing it to vibrate
Tympanic membrane -> auditory ossicles transmit sound to the faceplate of stapes at oval window -> vibration of perilymph and endolymph
The _______ vibrates at different points depending on the frequencies of sound present
Basilar membrane
Basilar membrane contains _______ that are shorter and stiffer near the oval window and longer and flexible near the helicotrema
Reed-like fibers
______ that vibrate on the basilar membrane stimulate local hair cells
The reeds (reed-like fibers)
Reed like fibers are shorter and stiffer near the ______ ; longer and flexible at the ________
Oval window
Helicotrema
High frequencies (short wavelengths) is detected near the _________ , low frequencies toward the _______
Oval window; helicotrema
What is the function of the round window?
Helps dissipate the pressure within the inner ear. Bc the cochlea is embedded in bone which is unyielding
Round window bulges in and out wiht the vibrations caused by the _______
Stapes
What are the differences of the internal hair cells and external hair cells
Internal hair cells- fewer of them. Primary receptors for hearing
External hair cells - more numerous. In some way control the sensitivity of the inner hair cells
____ are the primary receptors for hearing
Internal hair cells
What is the function of external hair cells?
In some way control the sensitivity of the inner hair cells
The hairs themselves in the organ of Corti are called _______
Stereocilia
Describe the hair cell function
As the basilar membrane fibers move up and down the reticular lamina rocks back and forth making the stereocilia that is embedded in the tectorial membrane bend
Bending of the stereo cilia in one direction cause ______ and in the other direction cause _______
Depolarization; hyperpolarization
______ and _________ contain perilymph
Scala vestibuli and scala tympani
________ communicates with the subarachnoid space around the brain and the composition is similar to CSF
Perilymph
_______ contains endolymph
Scala media
What secretes endolymph?
Stria vascularis of the tunica media
What is the composition of endolymph? Perilymph?
Endolymph: high concentration of K and low Na (the opposite of perilymph)
Perilymph: composition similar to CSF
Loudness detection is based on what?
Amplitude of vibration of the basilar membrane
What occurs to the hair cells with louder noises?
More inner hair cells on the fringes of the basilar membrane are stimulated causing spatial summation
More outer hair cells get stimulated as well
______ is how sound intensities are expressed in terms of the log of their actual intensities
Decibel Unit
A 10X increase in sound energy is called __________ and _______ is called a decibel
1 bel
.1 bel is called a decibel
________ sounds must be loud to be heard. ________ sounds can be heard at much lower amplitudes (frequency)
Low frequency
High frequency
After hair cells are stimulated, they synapse with _______
Spiral ganglion cells (bipolar)
The axons from the spiral ganglion form the ______ nerve
Cochlear part of the vestibulocochlear nerve. (Aka auditory nerve)
Axons of the cochlear nerve terminate where?
In both the dorsal and ventral cochlear nuclei in the medulla
In the auditory pathway, What directions can the secondary afferents project following synapsing at the cochlear nuclei?
1) cross over via the trapezoid body to the contralateral superior olivary nucleus then enter the lateral lemniscus
OR
2) ascend ipsilaterally into the lateral lemniscus
The lateral lemniscus terminates mostly into the ________ but also some fibers terminate in the _______
Inferior colliculus ; geniculate nucleus
________ is the sensory relay center for auditory input
Medial geniculate nucleus
Neurons from the medial geniculate nucleus travel through the ______ to terminate in the ________
Auditory radiations to terminate in the primary auditory complex of the temporal lobe
The secondary afferents of the auditory pathway can ascend ipsilateral into the _______ OR cross over via the _______ to the contralateral _________ then enter the _______
Lateral lemniscus
Trapezoid body; superior olivary nucleus; lateral lemniscus
Give a summary of the auditory pathway
Axons of the cochlear nerve -> dorsal and ventral cochlear nuclei in the medulla -> either cross over and go to the trapezoid body -> superior olivary nucleus to reach the lateral lemniscus or ascend ipsilateral to reach the lateral lemniscus
From lateral lemniscus -> mostly into the inferior colliculus and some to the medial geniculate nucleus
From medial geniculate nucleus -> auditory radiations -> Primary cortex of the temporal lobe
What are the 2 components of the auditory cortex?
Primary auditory cortex
Auditory association cortex
The Primary auditory cortex is brodmanns area _______. It is located in the ______.
41
Located in the superior temporal gyrus
_________ is where generally lower frequency sounds are processed anteriorly and other aspects of sounds are processed as well such as direction and onset of sounds
Primary auditory cortex (brodmanns area 41)
Direction and onset of sounds are processed in the ______
Primary auditory cortex
The auditory association cortex is located ________
Peripherally to the primary cortex in the temporal lobe and insula
Where is the meaning of sound processed?
Auditory association cortex
________ is necessary for speech interpretation
Wernicke’s area
________ is the ability to tell wher sounds are coming from
Direction discrimination
What are the two mechanisms of direction discrimination?
Time lag between the two ears
Difference in sound intensities from the two ears; sound is more muffled coming from the opposite side
Time lag between the two ears mechanism of direction discrimination is less helpful for sounds directly infront, behind or above a person. And is compensated by ________
Pinna facing forward
Direction discrimination of sound is largely processed in the ________
Superior olivary nuclei
In centrifugal signals, There are efferent fibers from ________ that send inhibitory signals to the _________.
Superior olivary nucleus ; hair cells in the organ of Corti
_______ produced from efferent fibers from superior olivary nucleus that sends inhibitory signals to the hair cells of the organ of Corti are thought to ________ certain sounds to help pick out tunes of interest
Centrifugal signals
Tune out
What are two types of deafness?
Nerve deafness and conduction deafness
Describe nerve deafness
Loss of hearing due to damage to the cochlea, cochlear nerve or parts of the CNS involved with hearing
Complete destruction of the cochlea or its nerve causes _______
Permanent nerve deafness
Describe Conduction deafness. And how is damage acquired?
Loss of hearing due to damage to the tympanic membrane or ossicles
Damage is often due to calcification or fibrosis
In conduction deafness the ______ is still possible as long as the cochlea is intact
Bone conduction
In age related nerve deafness what occurs?
A person’s bone conduction is a little less than air conduction and higher wavelengths are more effected.
_______ can occur due to middle ear sclerosis
Conduction deafness
In conduction deafness, the bone conduction is normal. Why?
Bc the cochlea is NOT damaged and can hear vibrations directly plied to the bone surrounding it
In conduction deafness, _______ is diminished due to the inability of the middle ear structures to transmit sound
Air conduction
What tests can be used to distinguish nerve vs conduction deafness
Rinne’s test
Weber’s Test
Normally sound stops being heard behind the ear on the ________, moving the tuning fork next to the ______ can be heard again
Mastoid
Meatus
In the _______ the tuning fork should be louder infront of the ear rather than behind it near the mastoid.
Rinne’s test
________ detects lateralization of sound. ( can you hear a buzzing noise when the tuning fork is placed midline?
Weber’s test
To test hearing hearing loss, _______ test tests for conduction and _______ test tests for localization
Conduction - rinne’s test
Localization - Weber’s test
There is no hearing loss when in the rinne’s test there is ______ and in the Webers test there is ______
Rinne’s test - air is greater than bone
Weber test - midline
Taste is primarily a function of ________, although taste experience is influenced by: ______, ______ and _____
Taste buds
Smell, tactile stimulation of tongue, chemical irritants such as capsaicin
What are the 5 categories of taste modalities?
Sour Salty Sweet Bitter Umami
What do the following taste modalities respond to? Sour Salty Sweet Bitter Umami
Sour- acids
Salty- ionized salts, mainly sodium
Sweet- sugar, glycols, alcohols, aldehydes, ketones, sulfonic acids
Bitter- long chain organic nitrogen containing molecules, alkaloids (drugs and plant toxins)
Umami- L-glutamate (MSG)
Taste buds are located within a large structure called _____
Papilla
Taste buds are composed of ________ clustered under a _______. These cells have _______ on their apical surfaces
Chemosensitive cells clustered under a taste pore.
These cells have taste hairs on their apical surface (microvilli)
What are the 3 papillae that have taste buds and their locations?
Circumvallate (vallate) papillae - V shaped line on posterior tongue
Fungiform- folate anterior surface of the tongue
Foliate - lateral folds of tongue
There re also some buds on the palate and tonsils
_______ papillae do not have tase buds and are the most numerous
Filiform
T/F: certain taste buds respond to certain or specific taste modalities
False. Taste buds are more integrated throughout the tongue than previously thought
Chemicals specific to a taste bud will bind to receptors on the taste cells and cause opening of ion channels. This depolarizes the membrane creating a _______
Receptor potential
_____ washes away the chemical to remove the stimulus from the taste bud
Saliva
Describe accommodation in the taste buds
Afferent fibers from taste buds accommodate rather rapidly o that the taste sensation tapers off after the initial stimulation
What is the taste pathway of the anterior 2/3 of tongue?
Lingual -> chorda tympani branch-> facial nerve -> tractus solitarius (solitary nucleus)
What is the taste pathway from the posterior 1/3 of tongue
CN IX-> tracts solitarius (solitary nucleus)
Describe the taste pathway of the base of the tongue and pharynx
Vagus nerve -> tractus solitarius
Where do the second order neurons travel from the tractus solitarius?
Go to the VPM of the thalamus just medial to where fine touch from face terminates
Where do third order neurons in the taste pathway go to?
The lower tip of the post central gyrus in the parietal cerebral cortex (gustatory cortex)
What are other connections from the tractus solitarius other than the VPM?
Superior and inferior salivatory nucleus which triggers salivation
Describe the taste pathway in general.
First order neruons come from chorda tympani (CN VII), CN IX, and CN X -> second order neurons to solitary nucleus -> either the superior or inferior Salvatory nucleus (salivation) OR -> VPM of thalamus.
From VPM of thalamus -> post central gyrus in the parietal cerebral cortex (gustatory cortex)
Where does smell/ the olfactory system lie in te nose?
Superior part of each nostril
The olfactory epithelium, the membrane contains what?
Bipolar olfactory cells which have cilia that project into the nasal cavity
_______ glands secrete mucus in the nose
Olfactory glands (Bowmans glands)
Describe olfactory cell depolarization
Odorant chemicals dissolve in the mucus then contacts cilia -> receptors on cilia use cAMP second messenger system to open ion channels -> depolarization of membrane
Olfactory cells adapt by about _______ in a few seconds then gradually adapt further until _______
50%
The odor is no loner detected
in the olfactory pathway, The olfactory cells axons penetrate the _______ and synapse in the olfactory bulb in regions called _______
Cribriform plate
Glomeruli
In the olfactory pathway the receptors of the same specificity all converge on the same _______
Glomerulus
In the olfactory pathway, axons leaving the glomerulus synapse with secondary neurons (_____ and ____ cells)
Tufted and mitral cells
Axons from _____ and _____ form the olfactory tract that goes to the CNS
Tufted cells
Mitral cells
The olfactory tract ends in one of the following 3 pathways, ______ , ______ or ______
Primitive olfactory system
Less old olfactory system
New pathway
________ system has to do with response to smell such as salivation and feeding responses
Primitive olfactory system (medial olfactory area)
What is the location of the primitive olfactory system (medial olfactory area)?
Septal nuclei anterior to the hypothalamus
What is the location of the less old olfactory system (lateral olfactory area)?
Pyriform cortex of temporal lobe and amygdala
What is the function of the less old olfactory system and what is another name for it?
Lateral olfactory system
Discriminates between tasteful and distasteful foods, memory of bad experience with a food
Describe the new pathway of the olfactory pathway
Some fibers pass through thalamus then project to the paleocortex in the anteriomedial portion of the temporal lobe
Probably helps with conscious analysis of odors
Sensory information is integrate and used to generate appropriate motor responses at 3 basic levels. What are those levels and what occurs at them?
Spinal cord - simple reflexes
Brain stem - more complex responses
Brain - complicated muscle skills
In cord reflexes, sensory signals enter the _______ then divides into 2 branches; one transmits signals to _____ and the other ______
Higher levels of CNS
Terminates in SC for local reflexes
What are the cells involved in cord reflexes?
Interneurons - integrative function of SC
Anterior motor neurons - gives rise to the fibers then leave the ventral roots in 2 types, alpha motor neurons and gamma motor neurons
What are the two types of fibers involved in anterior motor neurons ventral roots?
Alpha motor neurons
Gamma motor neurons
Alpha motor neurons have the _____ fiber type
Aalpha
_______ neurons branch multiple times as they enter skeletal muscles they innervate. Innervate a motor unit.
Alpha motor neurons
Axons of motor neruons extend from the ______ to the ______. There each axon divides into a number of _______ that form neuromuscular junctions with muscle fibers scattered throughout the muscle
SC -> muscle
Axon terminals
What are the characteristics of gamma motor neurons?
About 1/2 as numerous as alpha motor neurons
Transmit Agamma fibers and they innervate intrafusal fibers which are important for controlling muscle tone
Gamma motor neurons transmit through ____ fibers and they innervate special muscle cells called ______
Agamma ; Intrafusal fibers
What are intrafusal fibers important for?
Controlling muscle tone
Each muscle spindle contains _______ fibers that has both motor ____ and sensory _____ innervation
Intrafusal skeletal muscle fibers
Agamma
Ia and II
What are two types of intrafusal fibers?
Nuclear bag fiber
Nuclear chain fiber
What are the types of sensory neuron fibers involved in muscle spindles?
Ia- primary afferent or annulospiral ending
II- secondary ending or flower spray ending
Ia sensory neuron fibers in the muscle spindle are _______ or ______
Primary afferent or annulospiral ending
II sensory neuron fiber in the muscle spindle is _______ or ______
Secondary ending or flower spray ending
What are two responses of spindle sensory function?
Static stretch response
Dynamic stretch response
______ is a spindle sensory function where gradual stretch causes both primary and secondary endings to fire in proportion to the stretch
Static stretch response
________ is a spindle sensory function where stretch causes ONLY the primary endings respond dramatically
Dynamic stretch response
In the static stretch response, _____ stretch causes ________ to fire in proportion to the stretch
gradual stretch causes Both Primary and secondary endings fire
In the dynamic stretch response, _____ stretch causes ______
Sudden stretch causes ONLY the primary ending to respond dramatically
_______ neurons innervate the ends of the muscle spindle cells
Gamma motor neurons
The gamma motor neurons innervate the ends of the muscle spindle cells, therefore if they fire, it ______ tension in the center of the fiber where the _______ are
Increases
Sensory nerve endings are
_______ are gamma motor neurons that mainly effect the nuclear bag fibers
Gamma dynamic
______ are gamma motor neurons that mainly defect the nuclear chain fibers
Gamma-static
What do gamma dynamic neurons mainly affect?
Nuclear bag fibers
What do gamma static neurons mainly affect?
The nuclear chain fibers
What is the muscle stretch reflex mechanism?
Muscle stretch-> increased afferent signals ->SC-> increased efferent output though alpha motor neurons -> muscle contracts -> firing rate of afferent sensory neuron decreases
What are the 5 steps of the muscle stretch reflex pathway?
1) stretching of msucle spindle stimulates muscle spindles
2) activation of sensory neuron
3) information processing at motor neuron
4) activation of motor neuron
5) contraction of muscle which opposes the stretching of the muscle spindles
The muscle stretch reflex pathway is _______
Monosynaptic
What is the pathway of dynamic stretch responses?
Nuclear bag-> Ia afferent -> alpha motor neuron -> skeletal muscle (extrafusal)
What is the pathway of static stretch receptors?
Nuclear chain -> II afferent -> alpha motor neuron -> skeletal muscle (extrafusal)
With dynamic and static stretch response:
In ______ reflex functions to oppose sudden changes in muscle length And occurs in a few seconds
Dynamic
in dynamic vs static stretch responses:
In ______, Reflex functions help to maintain a the muscle at the new length. This occurs after the ______
Static
Dynamic
_________ helps to maintain the degree of muscle tone until the person decides to do something else with the muscle
Static stretch responses
What is an important function of the spindles?
Damping / smoothing
During normal msucle activity, when the _____ fibers contract, the _______ must also
Extrafusal
Intrafusal
What would occur if the extrafusal fibers contracted by the intrafusal fibers didn’t?
Spindles would become flaccid and therefore lose its sensitivity to stretch
And
Damping function would be lost
Reflex tests are used to asses the integrity of what?
The sensory and motor pathways to and from the SC, the cord itself and for certain neurological disorders
_______ is an encapsulated afferent nerve ending that is embedded within tendons
Golgi tendon organ
What stimulates the golgi tendon organ?
Increases in tension exerted on the tendon by the muscle or other force
What is the afferent innervation of the golgi tendon organ?
Ib
What are the functions of the dynamic and static reflexes in the golgi tendon reflex?
Dynamic: senses rapid changes in tension
Static: steady state response in proportion to muscle tension
What is the pathway of the golgi tendon reflex?
Tension -> Ib-> interneurons -> inhibits anterior motor neurons (alpha and gamma motor neurons)
What does the golgi tendon reflex prevent?
Excessive tension on a tendon that may cause damage to the muscle (tearing) or the tendon (avulsion)
What are the functions of golgi tendon reflex?
Equalize contractive forces among muscle fibers so that the load is distributed more evenly
Prevents excessive tension on a tendon that may cause damage to the muscle (tearing) or the tendon (avulsion)
_________ functions in conscious proprioception and the perception of body position
Dorsal column - MLS
_______ functions in unconscious proprioception and carry information to the cerebellum to appraise the brain about instantaneous changes occurring in the muscles and tendons
Dorsal spinocerebellar tract
What does the dorsal spinocerbellar tract do?
Carry information to the cerebellum to appraise the brain about instantaneous changes occurring in the muscle and tendons
What are other names for the flexor reflex? (3)
Withdrawal reflex
Pain reflex
Nociceptive reflex
Effect of the flexor reflex is most powerfully stimulated by ______
Pain
If a limb is painfully stimulated, flexors are likely to ________
Contract to move the limb away from the stimulus
If another part of the body besides a limb is stimulated by pain the muscles involved may not actually be _______ so therefore the better term would be _______ reflex
Flexors
Withdrawal
______ reflex is polysynaptic
Flexor reflex or withdrawal reflex
What is the polysynaptic path of the flexor reflex?
Nociception -> interneurons -> motor neurons
What are two reflexes that may accompany the flexor reflex?
Reciprocal inhibition
Crossed extensor reflex
Describe reciprocal inhibition
If the reflex causes flexion in a limb, there will also be inhibition of its antagonist (the extensor)
________ is a flexor reflex in the left limb causes extension in the right limb
Crosses extensor reflex
What are 4 more complex cord reflexes?
Positive supportive reaction
Steeping movements
Injury induced spasm
Muscle cramps
______ is a cord reflex where pressure on the foot tends to cause reflexive extension against the pressure
Positive supportive reaction
_______ is a cord reflex where much of the oscillating movements between the legs and arm swing is hard wired in the cord
Stepping movements
__________ is a cord reflex where pain from a significant injury, such as a bone fracture, causes reflex sustained contraction of muscles near the fracture
Injury induced spasm
_______ causes a similar phenomenon of injury induced spasm involving spasm of the abdominal muscles
Peritonitis
_______ is a cord reflex where local irritating factor ( metabolic issue, severe cold, ischemia, over exercise etc.) case contraction which exacerbates the irritation leading to a positive feedback situation called a ______
Muscle cramp
Cramp
What are some examples of autonomic reflexes in the cord?
Changes in vascular tone resulting from changes in skin heat
Sweat reflex due to surface heat
Intestinointestinal reflexes that control gut motility
Evacuation reflexes fr emptying the full bladder or colon
Most voluntary movements initiated by ______ are achieved when the cortex activated patterns of function stored in _________ - ___________. These ______ in turn send specific control signals to the muscles
Cerebral cortex
Lower brain areas - cord, brain stem, basal ganglia, cerebellum
Lower centers
_______ occupies about 1/3 of the frontal lobe
Motor cortex
The motor cortex occupies about 1/3 of the ______ lobes
Frontal
What are the 3 parts of the motor cortex?
Primary motor cortex
Premotor area
Supplementary motor area
What is the location of the primary motor cortex?
Pre central gyrus
Brodmanns area 4
In the primary motor cortex, the inferior body is controlled toward the _______ and the head is controllled toward the ______
Longitudinal fissure
Horizontal fissure
The primary motor produces _________ when stimulated
Discrete muscle movements
Large pyramid cells called ______ make up outgoing cells from layer V of the cortical layers of the primary motor tract
Beta cells
what are Betz cells
Large pyramidal cells that are outgoing cells from layer V
What are some characteristics of Betz cells?
Only 3% of outgoing fibers
Largest, fastest
Appear to be involved with direct connections with lower motor neurons (neuron that leaves the SC through the ventral root)
What is the location of the premotor area of the motor cortex
Anterior to the primary motor cortex
Describe the topographical map of the premotor area
Head - inferior and lateral
Lower body- superior and medial
________ generates more complex patterns of movement than the primary cortex
Premotor area
What are the connections (3) that the premotor area has?
Basal ganglia
Thalamus
Primary motor cortex
What is the location of the supplementary motor area of the motor cortex?
Mainly in the longitudinal fissure but extends somewhat onto the superior frontal cortex
_______ works with the premotor area to produce bilateral body wide coordinated movements such as positioning the body as background for more fine motor control of the hands
Supplemental motor area
________ is the motor speech area. It coordinates the muscles of the mouth, tongue and respiration adn larynx for speech
Broca’s area
_______ allows selecting new fixation points consciously
Voluntary eye field and head rotation
Loss of this area leads to motor apraxia. What is this area?
Hand skills
What are the motor pathways?
Corticospinal (pyramidal) tract
“Extrapyramidal” tract
What motor pathway tract is for detailed skilled movements particularly of distal limbs, this more direct pathway from brain to spinal cord is used
Corticospinal (pyramidal) tract
What motor pathway invovles motor signals that descend from the brain and involve the basal ganglia, cerebellum or brain stem for muscle control
Extra pyramidal tracts
________ tract is a motor pathway thats more for postural or generalized movements
Extra pyramidal tracts
The extrapyramidal tracts involves motor signals that descend from the brain and involve ______, __________ or ______ for muscle control
Basal ganglia, cerebellum, brain stem
In the cortex, the upper motor neurons of the corticospinal tract originate:
- 30% from _______
- 30% from ________ and ________
- 40% from _________
Primary motor cortex
Premotor and supplementary motor cortex
Somatosensory association areas
Regarding the corticospinal tract:
The upper motor neuron axons pass through the _______ -> _______ -> ______-> _______(medulla)
- Posterior limb of internal capsule
- cerebral peduncle (midbrain)
- longitudinal fasciculus of pons
- pyramids (medulla)
Regarding the corticospinal tract:
In the caudal medulla most fibers decussate then descend in the ______ tracts of the cord.
A few fibers do not decussate and descend via the ______ tract
Decussate - lateral corticospinal tracts
Do not decussate - ventral corticospinal tract
The few fibers that do not decussate and travel down the ventral corticospinal tract are for _____ (function)?
For bilateral posture movements controlled by the supplementary motor cortex
The upper motor neuron of the corticospinal tract terminates mostly on _____ in the _____.
Interneurons
Cord
The _________ neurons of the corticospinal tract synapse with the _________ neurons
Upper motor neurons
Lower motor neurons
Some cortical motor fibers terminate in the _________ (midbrain) via the _______ tract
Red nucleus
Corticorubral tract
Some cortical motor fibers terminate in the red nucleus via the corticorubral tract then fibers descend to the _______ of the spinal cord via the ________
Interneurons of the SC via the rubrospinal tract
________ tract appears to be accessory to the lateral corticospinal tracts
Rubrospinal tract
Describe somatosensory feedback
Input from muscle spindles and golgi tendon organs as described earlier
Tactile input triggers grasping motions or pressure on feet cause extension motions
________ reflex is important in helping “dampen” the motor movements initiated by the cerebral cortex. Part of the. Motive power is due to stimulation of the ______ reflexes
Stretch reflex
Spindle reflexes
Brain initiated motor movements to muscles is not accompanied by brain initiated inhibition to antagonistic muscles bc _________ reflex does it automatically
Spinal cord’s reciprocal inhibition reflex
Cord withdraw, walking, postural, scratch reflexes etc. can be activated by what?
Commands coming from the brain
What are examples of autonomic control of the brainstem control of motor function?
Respiration
Cardiovascular
Some GI
What are the examples of brainstem control of motor function (3)?
Autonomic control
Motor functions involving the reticular nuclei (pontine and medullary) and the Vestibular nuclei
What are the two reticular nuclei?
Pontine reticular nuclei
Medullary reticular nuclei
________ reticular nuclei excite antigravity muscles, gives rise to medial reticulospinal tract
Pontine reticular nuclei
The pontine reticular nuclei gives rise to __________ tract
Medial (pontine) reticulospinal tract
_________ nuclei work with the vestibular system which is also excitatory
Pontine reticular nuclei
Medullar reticular nuclei inhibit _______
Antigravity muscles
Medullary reticular nuclei gives rise to _________ tract
Lateral (medullary) reticulospinal tract
What tracts do the medullary reticular nuclei work with to allow voluntary override of the postural muscle activity
Corticospinal and rubrospinal tracts
______ reticular nuclei excite antigravity muscles
______ reticular nuclei inhibits antigravity muscles
Pontine
Medullary
______ nuclei are excitatory to postural muscles but is selective as to which muscles it excites based on input from the ______ system
Vestibular nuclei
Vestibular system
_______ and ______ contain sensory structures called maculae that have hair cells that are embedded in a gelatinous structures containing otoliths (statoconia) made of calcium carbonate
Utricle and saccule
The utricle and saccule contain sensory structures called _____ that have hair cells embedded in a gelatinous structure containing _______ made of calcium carbonate
Maculae; otoliths (statoconia)
Gravity pulls of these ______ therefore bending the hair cells in the utricle and saccule
Otoliths
The utricle senses static position of the head in respect to gravity best in the ______ position
Upright
The saccule sense static position of the head in respect to gravity best in the ______ position
Horizontal
The ______ and ______ detect linear acceleration
Utricle and saccule
In the _____ of each semicircular duct is a _______ with hair cells embedded in the sail- like structure called the ______
Ampulla; cristae ampullaris; cupula
Describe the semicircular duct orientations
Each duct is oriented to a different sagittal plane ( anterior, posterior and lateral (horizontal))
During rotational movement of the head, fluid due to inertia will not move while the membranes of the ducts move with the head. This bends the _______ and bends the ______
Cupula ; hair cells
What are semicircular ducts good at detecting?
Head rotation, angular acceleration, and prediction of malequillibrium
Describe vestibular postural reflexes
Sudden changes in orientation causes motor movement to “right” the orientation
Describe the vestibular postural reflex as a part of eye stabilization
Movement of the head counterbalances by movement of the eyes to keep them fixated on target
What are 4 other mechanisms that influence equillibrium
Neck proprioception
Body proprioception
Exteroreception
Visual information
_______ counterbalances the vestibular signals when the head is tilted but the body is upright
Neck proprioception
________ is involved in detecting weight distribution between feet and weight distribution between hindfoot and forefoot
Body proprioception
_________ is when feeling of wind on body causes one to lean a into it to keep balance
Exteroception
___________ can compensate for loss of equillibrium by neck proprioception, body perception and exteroception as long as the eyes are open
Visual information
In regards to the vestibular pathway:
Vestibular nerves from the vestibular apparatus -> ______ there it can pass to 3 different possible locations in the CNS
Vestibular nuclei
What are 3 examples of paths from the vestibular nuclei in the vestibular pathway?
Vestibular nuclei -> vestibulospinal tracts
Vestibular nuclei -> medial longitudinal fasciculus -> CN III, IV, VI (eye movement)
Vestibular nuclei -> parietal lobe by lateral fissure
What are the 4 vestibular nuclei?
Superior
Medial
Lateral
Inferior
What are the inputs to the superior and medial vestibular nuclei? Outputs?
Afferents from semicircular ducts
Efferent to eyes, neck, and head muscles
What is the function of the superior and medial vestibular nuclei?
Function to position head and eyes to correct for changes in equilibrium
What are the inputs and outputs of the lateral vestibular nuclei?
Input from utricle and saccule
Output to body
What is the function of the lateral vestibular nuclei?
To control righting reflexes of the body
What are the inputs and outputs of the inferior vestibular nuclei?
Input from the semicircular canal, utricle and saccule
Output to cerebellum and reticular formation
What is the function of the inferior vestibular nuclei?
Coordinates the function of the vestibular system with these motor control areas
When looking at sound waves, the crests correspond with _______; the throughs correspond with _________.
crests- compression
Troughs- rarefraction (decompression)
The shorter the wavelength the higher the _______ and the higher the _____
Frequency and pitch
The higher the amplitude of sound, the __________ it is
Louder
______ functions in inhibition of hearing or in other words “selective hearing”
Centrifugal signals
